import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 */
public class TestDemo {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int ret = 1;
        for (int i = 1; i <= n; i++) {
            ret *= i;
        }
        System.out.println(ret);
    }
}
